Warehouses and manufacturing facilities commonly have sectional overhead doors to keep weather, dirt, debris and insects from entering the structure. New federal requirements for air standards in employee work areas mandate a controlled environment. Sanitation is a consideration that has brought about changes in the methods of opening sectional overhead doors to vent and cool buildings.
The new requirements are affecting building construction. Sectional overhead doors may need to be kept closed to meet air standard requirements, leaving the doors vulnerable to damage. Protecting sectional overhead doors from potential damage has thus become a concern in industry.
Several types of protection devices have been developed for sectional overhead doors to prevent damage from an impacting force. U.S. Pat. No. 5,720,332 to Nachreiner (1996) discloses a complex impact absorbing panel assembly. However, only the bottom panel of the door is protected, leaving the rest of the door unprotected. The bottom impact absorbing panel provides no protection if the door is in the fully opened position. Also, the impact panel has a series of security locks, which, if left unlatched, create a security problem.
Although security doors address different issues, protection can be provided by installing a second complete, sectional overhead security door and track adjacent to a sectional overhead door. U.S. Pat. No. 5,408,789 to Plfeger (1993) discloses a security sectional overhead door including a safety beam. However, the small area of the safety beam leaves the rest of the door unprotected from damage by vehicles or freight, and damage to both the sectional overhead door types is possible. Thus, if the sectional overhead security door were to provide protection, the operator would be required to perform additional labor for closing. Also, maintenance costs may be significant for service on the sectional overhead security door and the sectional overhead door.
Several types of thin, flat barriers exist. For example, the U.S. Pat. No. 4,356,668 to Wagner (1980) discloses barriers for sectional overhead door protection. Although inexpensive to manufacture, the barriers can be used only once in most cases. The several barriers disclosed are dependent on an elaborate system of pulleys and switches requiring periodic service to keep the systems operational.
Also, U.S. Pat. No. 5,649,396 to Carr (1997) discloses a safety barrier for use across a vehicle passageway to prevent a vehicle from moving off the end of a loading dock. However, it does not appear that the barrier provides protection for an adjacent sectional overhead door from impact by, say, a forklift fork or a pallet. Also, there does not appear to be protection for the sectional overhead door while in the opened position.
Known forms of sectional overhead door protection devices suffer from a number of disadvantages in that they: (a) Fail to provide protection for the sectional overhead door while it is in the fully opened position; (b) Become complicated with pulleys, switches and the like that require high maintenance and extra expenses; (c) Fail to withstand multitudes of impacts; and (d) Lack an ability to alert operators that the protection device is undergoing stress.